Process of making filled abrasive wheels.



V CLARENCE'ROSCOE KING, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO NORTON COMPANY, A CORPORATION OF MASSACHUSETTS.

PROCESS OF MAKING FILLED ABRASIVE WHEELS.

No Drawing.

To an whom it may concern:

Be it known that I, CLARENCE RosCoE KING, a citizen of the United States, residing at l/Vorcester, in the county of WVorcester and State ofMassachusetts, have invented a new and useful Process of Making Filled Abrasive Wheels, of which the following is a specification.

This invention relates to a process of making filled abrasive wheels and particularly to the process of making a filled wheel having certain distinguishing characteristics.

The details of my improved process are fully described in the following specification and the novel features thereof .will be specifically defined in the appended claims.

I have discovered that when certain types of abrasive wheels are filled with a material having certain definite characteristics, the efiiciency of the wheels as grinding tools is thereby greatly increased. The increase in efiiciency is most marked when this treatment is applied to abrasive wheels having a porous unitary structure, such wheels being ordinarily formed by uniting loose grains of abrasive material by some form of silicate binder.

The most common types of these wheels are commercially known asvitrified wheels and silicate wheels. In the first class, the silicate binder is composed largely of clay mixed with other mineral silicates, this mixture being partially fused when burned in a kiln and thus forming a porous mass in which the abrasive particles are securely held, the bond partaking largely of the nature of porcelain or glass. In the silicate wheels, the principal binding material /is silicate of soda commonly known as water glass. This silicate, when mixed with certain mineral powders and heated to a sulficient temperature, reacts with the other materials and forms a hard porous mass similar in many respects to the vitrified wheels.

In the use of these wheels in grinding the efliciency of the abrasive is reduced by glazing and also by the filling or loading of the wheel. The term glazing is used to indicate the action of the work upon the abrasive particles by which they lose their sharp edges and become smooth and ineffective, while the term loading relates to the filling up ofthe voids in the face of the wheel by particles of the material being Specification of Letters Patent.

Application filed May 28,, 1914. Serial No. 841,679.

ground, this loading of the face causing the cutting edges of the abrasive to be covered. 1 have discovered that the efficiency of such a wheel may be greatly increased by filling the voids of the porous structure with some material which is normally solid but which becomes fluid and sticky at the temperatures ordinarily attained in the grinding operation. l/Vhile there are a considerable number of materials possessing these characteristics, I have found that ordinary rosin is particularly well adapted forthe purpose stated.

In the carrying out of my improved process, I form an abrasive wheel, preferablywith a silicate binder, and having a porous unitary structure. In order that the voids of the wheels may be thoroughly filled 1 heat the wheel to a temperature substantially the same as that of the melted rosin and then dip the wheel in the rosin. I have found it advantageous to allow the wheel to remain in the rosin bath for a considerable period of time, usually about onehour, so that all of the voids in the structure may be thoroughly filled with the liquid rosin. I then remove the wheel'from the rosin bath and allow it to cool until the rosin is solidified within the voids.

In order that the filling material may be evenly distributed throughout the structure I find it advisable to frequently turn the wheelsduring the cooling process. This result may be attained by mounting the wheel upon an arbor and slowly revolving it thereon or by laying the wheel upon its fiat side and frequently reversing its position. Ihave proved by actual tests that the efficiency of an abrasive wheel is increased in a most remarkable degree by this treatment. As the rosin is solid at ordinary temperatures and is very sticky at grinding temperatures the wheels thus treated will not get out of balance by the flowing of the rosin from one portion to another.

The action of the filling material upon the 1 00 it is so brittle that it may be dislodged and thrown oif during the revolution of the wheel.

'While I have described the use of rosin for carrying out my invention I do not Wish to be limited thereto as I have previously pointed out that any ingredient having the characteristics of being normally solid at I claim and desire to secure by Letters Pat- -ent is 1. The process of making a filled abrasive wheel which consists 1n forming an abrasive wheel with a silicate binder and having a to a moderate temperature, dipping said porous unitary structure, heating said wheel wheel into a hot melted material which is solid at ordinary temperatures and becomes fluid and sticky at grinding temperatures and thereafter cooling said wheel.

2. The process of making a filled abrasive wheel which consists in forming an abrasive wheel with a porous unitary structure, heating said wheel to a moderate temperature, filling the voids in said wheel with a hot melted material which is solid at ordinary temperatures but becomes fluid and sticky at the temperatures attained in grinding, removing and cooling said wheel to solidify said material, and slowly turning said Wheel during the cooling operation so that the absorbed filling material may be retained within the wheel and may be distributed with substantial uniformity throughout the porous structure. In testimony whereof I have hereunto se my hand, in the presence of two subscribing witnesses.

CLARENCE ROSCOE KING.

Witnesses:

CHAS. T. HAWLEY, C. FORREST WESSON. 

